Editing Pontiac V8 engine (section)

{{multiple issues|
{{More citations needed|date=January 2010}}
{{original research|date=October 2016}}
}}
{{Infobox automobile engine
| name = Pontiac V8 engine
| image = 1965 Pontiac GTO engine 01.jpg
| caption = [[Pontiac GTO#1965|1965 Pontiac GTO]] [[Tri-Power]] 389 Trophy V8
| manufacturer = [[Pontiac (automobile)|Pontiac]] ([[General Motors]])
| production = 1955–1981 [[Pontiac Assembly]]<br />(engine block and heads)<br />[[Saginaw Metal Casting Operations]]
| aka = ''Strato Streak''
| configuration = 90° [[V8 engine|V8]]
| turbocharger = [[Garrett AiResearch|Garrett]] TBO-305 (in 301)
| valvetrain = [[Overhead valve engine|OHV]] 2 valves per cyl.
| fueltype = [[Gasoline]]
| fuelsystem = [[Rochester Products Division|Rochester]] or [[Carter Carburetor|Carter]] carburetors<br />[[Fuel injection]]
| coolingsystem = [[Radiator (engine cooling)|Water-cooled]]
| displacement = {{ubl|{{cvt|265|cuin|L|1}}|{{cvt|287|cuin|L|1}}|{{cvt|301|cuin|L|1}}|{{cvt|303|cuin|L|1}}|{{cvt|317|cuin|L|1}}|{{cvt|326|cuin|L|1}}|{{cvt|347|cuin|L|1}}|{{cvt|350|cuin|L|1}}|{{cvt|370|cuin|L|1}}|{{cvt|389|cuin|L|1}}|{{cvt|400|cuin|L|1}}|{{cvt|421|cuin|L|1}}|{{cvt|428|cuin|L|1}}|{{cvt|455|cuin|L|1}} }}
| bore = {{ubl|{{cvt|3.72|in|mm|1}}|{{cvt|3+3/4|in|mm|1}}|{{cvt|3.78|in|mm}}|{{cvt|3+7/8|in|mm|1}}|{{cvt|3.9375|in|mm}}|{{cvt|4|in|mm|1}}|{{cvt|4+1/16|in|mm|1}}|{{cvt|4+3/32|in|mm}}|{{cvt|4.121|in|mm|1}}|{{cvt|4.1525|in|mm}}|{{cvt|4.342|in|mm}} }}
| stroke = {{ubl|{{cvt|2.84|in|mm|1}}|{{cvt|3|in|mm|1}}|{{cvt|3+1/4|in|mm|1}}|{{cvt|3.5625|in|mm}} }}
| block = [[Cast iron]]
| head = Cast iron
| weight = {{cvt|550|to|650|lb|kg}}{{cn|date=May 2024}}
| compression = 7.9:1, 8.0:1, 8.4:1, 8.5:1, 8.6:1, 8.9:1, 10.0:1, 10.25:1, 10.5:1, 10.75:1, 11.0:1
| redline = varies
| power = {{cvt|120|-|310|hp|0}} SAE (370 bhp)
| torque = {{cvt|245|-|500|lbft|0}}
}}

The '''Pontiac V8 engine''' is a family of [[overhead valve]] 90° [[V8 engine]]s manufactured by the [[Pontiac (automobile)|Pontiac Division]] of [[General Motors Corporation]] between 1955 and 1981. The engines feature a cast-iron block and head and two valves per cylinder. Engine block and cylinder heads were cast at [[Saginaw Metal Casting Operations]] then assembled at [[Tonawanda Engine]] before delivery to [[Pontiac Assembly]] for installation.

Initially marketed as a {{cvt|287|cuin|L|1}}, it went on to be manufactured in displacements between {{cvt|265|cuin|L|1}} and {{cvt|455|cuin|L|1}} in carbureted, [[fuel injected]], and [[turbocharged]] versions. In the 1960s the popular {{cvt|389|cuin|L|1}} version, which had helped establish the [[Pontiac GTO]] as a premier [[muscle car]], was cut in half to produce an unusual, high-torque [[inline four]] economy engine, the [[Pontiac Trophy 4 engine|Trophy 4]].

Unusual for a major automaker, Pontiac did not have the customary "small-block" and "big-block" engine families common to other GM divisions, Ford, and Chrysler. Effectively, production Pontiac V8 blocks were externally the same size (326-455) sharing the same connecting rod length 6.625 in (168.3&nbsp;mm) and journal size of 2.249" (except for the later short deck 301 and 265 produced in the late 1970s and early 1980s before Pontiac adopted universal GM engines). The crankshaft stroke and main journal size changed among the years with the more popular 389CI and 400CI having a 3.00" diameter main journal and the 421/428/455 sharing a larger 3.25" diameter main journal.

The V8 was phased out in 1981, replaced by GM "corporate engines" such as the [[Chevrolet small-block engine#3.736 in bore family (1976–1998)|Chevrolet 305]] cu in small block V8.